1. Field of the Invention
The present invention relates to a power supply system absorbing an extra length of a wiring harness by using a constant force spring for supplying continuously electric power, for example to a sliding door of a vehicle.
2. Description of the Related Art
FIGS. 11A, 11B show an embodiment of a conventional power supply system (for example, see Patent Document 1).
The power supply system is fixed vertically in a sliding door 41 of a vehicle, and includes a protector (casing) 50 made of synthetic resin for receiving a wiring harness 43 to be bent freely, and a metallic flat spring 44 forcing the wiring harness 43 upwardly in the protector so as to absorb an extra length of the wiring harness 43 by forcing the wiring harness toward a curved surrounding wall 54 along a vertical wall 53 of the protector 50 by a force of the flat spring 44.
The wiring harness 43 is wired from a long bottom opening 55 of the protector 50 through a traversing area 46 to a harness fixer 60 in the vicinity of a step 48 of a vehicle body 47 so as to move swingably back-and-forth in a front-rear direction of the vehicle. Electric wire portion 43a at one side of the wiring harness is led from a front side of the protector 50 to a side of the sliding door for continuously supplying power to an electric apparatus and an auxiliary apparatus (not shown) at the side of the sliding door.
The protector 50 is structured by a protector base 51 and a protector cover 52. After mounting the wiring harness 43 and the flat spring 44 inside the protector 50, the protector base 51 and the protector cover 52 are locked and fixed with each other.
The flat spring 44 is fixed in a bottom area at a front-end of the protector 50 together with the wiring harness 43 (fixed portion of the flat spring is marked with “59”). A plastic cap 49 is fixed at an end of the flat spring 44. The wiring harness 43 is supported slidably by the cap 49.
The wiring harness 43 is formed by covering a plurality of electric wires 43a with a plastic corrugate tube 43b. An end of the corrugate tube 43b is fixed with an adhesive tape in the bottom area at the front end of the protector 50. The corrugate tube 43b is formed by arranging alternately ribs and groves like bellows so as to have a good flexibility. The each electric wire 43a of the wiring harness 43 in the traversing area 46 is safely protected by the corrugate tube 43b from outer interference, water drops, and dust.
FIG. 11A shows the sliding door 41 in a complete close condition. FIG. 11B shows the sliding door 41 in a half-open condition nearing a full-open condition. When the sliding door 41 is in the complete close condition, the wiring harness 43 is pulled backwardly. When the sliding door 41 is in the full-open condition, the wiring harness 43 is pulled forwardly. When the sliding door 41 is in the half-open condition, the wiring harness 43 tends to droop downwardly, but the wiring harness 43 is forced upwardly by the flat spring 44, so that a slack (an extra length) of the wiring harness 43 is absorbed and catching of the wiring harness caused by drooping is prevented.
FIG. 12 shows another embodiment of the conventional power supply system (see Patent Document 2).
The power supply system 61 for supplying power continuously to a sliding door or a sliding seat (not shown) of a vehicle, which have a long sliding length, includes a long slim casing 62 having a long narrow first guide slit 63 and a long narrow second guide slit 67, a pulley 64 moving back and forth along the first guide slit 63, a long compression spring 66 biasing the pulley 64 through a block 65 along the first guide slit 63, and a slider 68 moving back-and-forth along the second guide slit 67. One end 69a of the wiring harness 69 is fixed at the casing 62 and led to an outside of the casing 62. A middle area of the wiring harness 69 is formed into a U-shape along the pulley 64. The other end 69b of the wiring harness 69 is led to the outside of the casing 62 through the slider 68.
When the power supply system 61 is installed vertically at the sliding door, the one end 69a of the wiring harness at a fixed side is arranged at the sliding door and the other end 69b of the wiring harness at a movable side is arranged at a vehicle body. When the power supply system 61 is applied at the sliding seat, the power supply system 61 is arranged vertically or horizontally at a floor of the vehicle body, and the one side 69a of the wiring harness at the fixed side is arranged at the vehicle body, and the other end 69b of the wiring harness at the movable side is arranged at the sliding seat.
A power supply system, which uses a compression spring formed into a wave-shape by bending a flat spring instead of the compression coil spring 66, similar to the power supply system shown in FIG. 12 is disclosed in Patent Document 3.
[Patent Document 1] Japanese Published Patent Application No. 2001-354085 (FIGS. 4 and 7)
[Patent Document 2] Japanese Published Patent Application No. 2006-50841 (FIG. 2)
[Patent Document 3] Japanese Published Patent Application No. 2006-320145 (FIG. 1)